Uncle Abner: Master of Mysteries by Melville Davisson Post

THE pioneer was not the only man in the great mountains behind Virginia. Strange aliens drifted in after the Colonial wars. All foreign armies are sprinkled with a cockle of adventurers that take root and remain. They were with Braddock and La Salle, and they rode north out of Mexico after her many empires went to pieces.

I think Doomdorf crossed the seas with Iturbide when that ill-starred adventurer returned to be shot against a wall; but there was no Southern blood in him. He came from some European race remote and barbaric. He was a huge figure of a man, with a black spade beard, broad, thick hands, and square, flat fingers.